The present invention relates to corrugated paperboard containers that are used to ship heavy products during shipment, and more particularly, to an improvement to such containers to ensure scaling and integrity of the container against tampering or contamination.
In the food packaging industry, products are often packaged in a container that must be sealed against tampering and made to maintain integrity during shipping, storage, and handling. This is typically done by forming a corrugated tray, loading the product into the tray, and then sealing the tray closed. The containers used for shipment of refrigerated fresh meats, in particular, generally include cover panels that fold inward from upright side panels of the tray. The cover panels include side tabs (also called xe2x80x9cglue tabsxe2x80x9d) that are glued to the exterior surfaces of the tray""s upright end panels. See, for example, the container of U.S. Pat. No. 5,261,594. As shown in the ""594 patent and in the prior art container of FIG. 1, these tabs have historically been independently glued to the end panel.
A more recent innovation is the use of side tabs that overlap and are laminated to one another. (As used herein, the term xe2x80x9claminatedxe2x80x9d means adhered together.) These overlapping laminated tabs have presented some new and difficult challenges to fully sealing the top of a box. During assembly, a tray former creates the basic box shape of a bottom panel with upright side walls. Next, vacuum-packed meat product is placed in the tray and the combination is moved to a sealing area. Glue is applied to the side tabs and to the overlapping area of the cover panels, which are folded from their respective side walls. The container is then placed in a compression area. In the compression area, the tabs are held against the side panels for a period of time.
There are a number of problems associated with the sealing process for these types of containers. It can occur that the tabs are inappropriately folded back and glued against the upper surface of the cover during the sealing process. This is due in part to the configuration of known sealing conveyor systems, where a steel plow bar guides the tabs of the forward end of the container. When this occurs, the tabs are then not available to be properly glued to the end panels of the container. The tabs generally stick out and can become mangled against machine components and other adjacent containers.
A further problem is that, occasionally, the tabs come loose from the end panels after the container has left the final compression area. Both of these problems leave the cover unsecured, which is undesirable for stopping tampering and/or contamination. In addition, an unsecured cover can cause stacked containers to xe2x80x9ctelescopexe2x80x9d into one another, i.e., upper containers crushing down into lower containers when placed in a vertical stack. The present invention addresses these and other problems as well.
In accordance with the teachings of the present invention, a cover panel improvement is described for a container having a bottom panel, side walls, end walls, and an open top. The improvement includes first and second cover panels connected to the side walls. Each cover panel includes side tabs that extend outwardly and fold down onto the end walls of the container. Portions of the cover panel overlap, as do portions of the side tabs. Various embodiments are provided regarding the size, shape, and placement of heavy and zero crush areas in the side tabs and cover panels. The heavy crush areas are used to reduce the overall thickness of the side tabs where overlapped. Openings may be used along the hinge line between the side tabs to help in properly forming the respective hinge line. Likewise, a spine may be used to help maintain tab stiffness.